Ink jet recording apparatus

Abstract: An ink jet recording apparatus comprises a carriage (2) movable in a given direction with a recording head (1) which is detachably mountable on it and provided with discharge ports for discharging liquid. The apparatus is arranged to include a sensor (21) for detecting the presence or absence of the carriage (2), the recording head (1), and at least one of the ink containers. This sensor (21) is provided for the main body of the apparatus and positioned within the movable range of the carriage (2). With this arrangement, it is possible to simplify the structure required for detecting whether or not these vital elements for recording are installed without any auxiliary power-supply or memory means.

Description: The present invention relates to an ink tank according to claim 1. Moreover, the present invention relates to an ink jet recording apparatus according to claim 3 and to a method for detecting an ink amount in an ink tank according to claim 8. From the document PATENT ABSTRACTS OF JAPAN vol.012 no. 120 (M-685), 14 April 1988 & JP-A-62 246 740 (CANON INC) 27 October 1987 a generic ink tank is known. In order to detect the amount of ink remaining in the ink tank, a blocking float disposed within the ink tank reflects the incident light back towards the source. This is detected by the light receiving element as an absence of light which provides an indication as to the amount of ink remaining in the ink tank. There has been known an ink jet recording apparatus for recording by discharging fine ink droplets. This apparatus is advantageous over the apparatuses of other types because of its higher recording speed, easier recording in color, capability of recording not only on a regular sheet, but also on a cloth or other media, a lesser noise, and a higher quality among other features. In general, the recording head of an ink jet recording apparatus has ink discharging ports of one to approximately 200 or 1,000 to approximately 2,000 in order to record on the entire recordable area, while allowing the head to scan a recording medium correlatively. The main scan is such that the carriage on which the recording head is mounted reciprocates to scan for the correlative movement. The subscan is such that a recording medium is scanned in one way in relation to the recording head. Here, the recording head mounted on the carriage is arranged detachably from the carriage or an ink tank which contains ink to be supplied to the recording head is arranged detachably from the recording head. In the former arrangement, the recording head is replaced with a normal one for use if any malfunction takes place in the head or replaced with a new one completely when ink is finished in case of a recording head being arranged integrally with an ink tank. In the latter arrangement, only the ink tank can be replaced with a new ink tank for use while the recording head remains unchanged when ink is finished. However, since the head or the ink tank or both are detachably mounted on the carriage, whether or not the recording head or the ink tank is installed correctly must be examined manually by the user or automatically by the apparatus itself for confirmation when executing a recording operation. An examination of the kind by a user tends to be incomplete, while the automatic examination by a recording apparatus requires a sensor on the carriage. The sensor should be capable of transducing each event of the installation of a recording head or an ink tank into electrical signals, and transmitting them to the main body of the recording apparatus through flexible cables in order to make the required confirmation, and determine whether or not the installation is correctly carried out. However, according to the above-mentioned conventional technique, there is a need for a considerable size of space for the arrangement of the flexible cables, which tends to make the size of the apparatus larger inevitably. Also, the use of durable cables results in a higher cost. Therefore, it is advisable to avoid any provision of flexible cables for the transmission of the electrical signals or it is advisable to minimize the number of cables for this transmission. Also, if a sensor must be mounted on the carriage, the weight of the movable unit becomes heavier that much, necessitating the power of the motor for driving the carriage to be increased accordingly. Further, it take a longer time for the carriage to arrive at a constant speed. As a result, not only the recording speed is reduced, but also, a problem is encountered in that the apparatus should be made larger to the extent that the traveling distance of the carriage is made longer. Also, among such ink jet recording apparatuses, there has been known an apparatus which is arranged to detachably install an ink cartridge in the main body of the apparatus or on a carriage as a source of ink supply so that the provision of ink can be made easily along with the consumption of ink for recording. An ink cartridge of the kind is replaced manually by the operator for use. Further, there has been known an apparatus which is arranged to provide a function to prompt the operator to replace ink cartridges by detecting the ink remains when such an ink cartridge as above is used. However, in the above-mentioned ink cartridge, it is technically difficult to detect the ink remains exactly. Also, it costs extremely high if such a detection should be adopted. With a view to solving the problem, therefore, a method is proposed for detecting the ink remains in such a manner that the number of ink discharges from the head is counted, and the counted number is stored in a memory arranged in the main body of the apparatus, thus giving a warning when the stored number reaches a predetermined number of ink discharges. To effectuate this method, it is also necessary to reset the counter arranged for storing the counted number of ink discharges in the main body of the apparatus each time the ink cartridge is replaced. In this case, a switch and a detector for detecting the attachment and detachment of an ink cartridge must be provided. If the required resetting should be carried out by switching, it results not only in an additional cost, but also, in the operations imposed up the operator to execute such as depressing a start key and a reset key in addition to the replacement of the ink cartridges itself. This requires a considerable amount of work on the part of the operator. Also, the cost is inevitably increased by the additional provision of the detector. Moreover, the flow of ink in the ink jet head or in the ink supply pipe should be interrupted when the ink cartridges are replaced. It is then necessary to exercise an extra suction from the ink discharge surface in order to fill ink in the ink passages up to the ink discharge ports. As described above, there is a need for resetting the counter as well as exercising the extra suction when ink cartridges are replaced in a conventional ink jet recording apparatus. Also, it is necessary to detect whether or not the ink cartridge is installed correctly before these extra operations are performed. Here, in a thermal transfer serial printer, it has been known traditionally that a structure is arranged for detecting the position of a carriage, the information regarding an ink ribbon cassette, and the end of the ink ribbon in it by use of an optical sensor provided in the home position for detecting a discriminating portion given to the carriage, a discriminating portion given to the ink ribbon cassette, and a window arranged for detecting the end of the ink ribbon (as disclosed in Japanese Patent Laid-Open Application No. 62-60680, for example). In the thermal transfer printers, there is no possibility that the thermal head is damaged, even if no ink ribbon cassette is mounted on the carriage or a printing is erroneously carried out in a state where the ink ribbon in the ink ribbon cassette is used up. In an ink jet recording apparatus, however, there are some cases where the recording head itself should be replaced if the recording head is driven without mounting an ink cartridge or with an ink cartridge but having no ink in it (or with an ink tank which is formed with a recording head to provide an integrated unit, but having no ink in it), because the air and bubbles are mixed in the fine ink discharge ports or ink passages, thus inviting the disabled discharge of ink from the recording head. Also, in a recording head which discharges ink by use of thermal energy, the heater units may be damaged due to excessive heat in such cases. Therefore, in an ink jet recording apparatus, a technique required for detecting the presence or absence of an ink cartridge on a carriage or of the ink remains in the cartridge is vital to the life of the recording head. Particularly, in consideration of the current technical tendency which results in more frequent replacements of ink containers because of the prolonged life of the head itself, necessitating the replacement of the ink containers more often or in the adoption of a smaller ink container along the miniaturisation of the apparatus itself, which also necessitates the replacement of the ink containers more often, the above-mentioned detection technique becomes increasingly more important in recent years. With a view to solving the problems associated with the conventional technique as described above, it is an object of the present invention to provide an ink jet recording apparatus capable of easily detecting whether or not ink (or some other liquid) to be discharged from an ink jet recording head is available on a carriage. Moreover, the present invention shall provide an ink jet recording apparatus capable of easily detecting the presence or absence of an ink container on a carriage or the presence or absence of ink remains in the ink container. Furthermore, the present invention shall provide a method for determining an ink amount in an ink tank. The above-stated object is achieved by means of the combination of the features defined in claim 1. Preferred embodiments of the ink tank according to claim 1 are disclosed in the subclaims. The object is also achieved by means of the ink jet recording apparatus according to claim 3. Preferred embodiments thereof are set forth in the subclaims. Moreover, the object is achieved by means of the method for determining an ink amount in an ink tank according to claim 8. In the following the invention is further illustrated by embodiments with reference to the enclosed figures. Fig. 1 is a perspective view schematically showing another embodiment of an ink jet recording apparatus according to the present invention. Fig. 2 is a perspective view schematically showing the ink jet recording head represented in Fig. 18. Fig. 3 is an exploded perspective view schematically showing an ink jet recording head and a carriage. Fig. 4A is a side view schematically showing an optical sensor. Fig. 4B is a front view schematically showing the optical sensor. Fig. 5 is a block diagram showing a control system for a sensor and a controller. Fig. 6A illustrates a detection signal at the time of normal operation. Fig. 6B illustrates a detection signal at the time of abnormal operation. Fig. 7A illustrates a case in which a mechanical switch is used as a sensor. Fig. 7B illustrates a detection signal at the time of normal operation. Fig. 8 is a view schematically showing the positional relationship between a recording head dually functioning to detect the ink remains, and a sensor. Fig. 9 is a view schematically illustrating another embodiment of a recording head having a structure which dually functions to detect the ink remains. Fig. 10 is a view schematically illustrating a structural example of detecting a specific position of liquid level in an ink cartridge. Fig. 11 illustrates an example of electrical signal detected according to the structural example shown in Fig. 10. As shown in Fig. 1, when a recording apparatus 210 is in a recording operation, a recording medium 216 is fed by a feed roller 217 in the direction indicated by an arrow A. Further, it is exhausted by an exhaust roller 218 in the direction indicated by an arrow B. This movement is the subscan. During this period, the recording head 212 mounted detachably on a carriage 211 reciprocates along a guide shaft 215 by the movement of a lead screw 214 rotated by a motor for driving the carriage. This movement is the main scan. When the main scan is in operation, the subscan is at rest. During the period of a main scan, the ink droplets are discharged from the discharge ports of the recording head 212 as required in response to the inputted data. A flexible cable 219 is for inputting the aforesaid data and control signals to the recording head 212. An ink tank 221 for black ink and an ink tank 222 for color ink are for retaining each of the color ink to be supplied to the recording head 212. Each of the ink tanks 221 and 222 is also detachably mountable on the carriage 211. As described above, the recording head 212 is structured to be detachably mounted on the carriage 211. Should any trouble take place in the recording head 212, it is possible to replace such a recording head 212 with a regular product. Also, each of the ink tanks 221 and 222 are structured to be exchangeable. When ink is totally consumed after a given amount of recording operation, it can be replaced with a new ink tank. As shown in Fig. 2, there is arranged for each of liquid passages in the ink jet recording head 212, the electrothermal transducer 204 to which an applied voltage is supplied for generating the thermal energy in order to discharge recording liquid from each of the plural discharge ports 207 which are arranged in an array. When a driving signal is applied, each of the respective electrothermal transducers 204 generates thermal energy to create film boiling in the ink liquid passage for the formation of air bubble in it, and then, by the development of this air bubble, an ink droplet is discharged from each of the discharge ports 207. Fig. 3 is an exploded perspective view showing the recording head and the carriage. The recording head 212 is mounted on the carriage 211. Further, the ink tank 221 for black ink and the ink tank 222 for color ink are connected to the recording head 202 through each individual connecting pipe 220. The interior of the ink tank 222 for color ink is partitioned for yellow, magenta, and cyan separately. The number of the discharge ports 207 for discharging ink is 136 in total. In Fig. 3, there are arranged from the above, 24 ports for yellow, 24 ports for magenta, and 24 for cyan, and 64 for black in that order. Now, the features of the present embodiment will be described. Fig. 4A is a side view showing a sensor. Fig. 4B is a front view showing it. As shown in Fig. 1 to Fig. 4B, the sensor 230 is fixed to the main body of the recording apparatus so that it can be positioned within the movable range of the carriage 211 of the recording apparatus 210. This sensor 230 is an optical sensor. A beam is emitted from the light emitting portion 231 thereof, and the sensing is effectuated by receiving the beam reflected from an object by use of the photodetecting portion 232. A slit 233 is arranged in front of the photodetecting portion 232 in order to make the detecting orientation of the reflected beam better, thereby to enhance the precision of detection. The electric circuit for the sensor 230 is structured so that a high (H) level signal is output to a controller which will be described later when there is an object immediately before the sensor 230, and a low (L) level signal is output thereto if there is no object. If the object has a good absorption of light, there is a possibility that the low (L) level signal is output even if an object is present. Therefore, it is desirable to use a material having a particular characteristics of light reflection for an object to be sensed, that is, the surfaces of the carriage 211, the recording head 212, and each of the ink tanks 221 and 222. As shown in Fig. 5, the sensor 230 is connected to the controller 234 of the recording apparatus 210 (see Fig. 1), and on the indication panel 219, whether the sensor 230 outputs a low (L) level signal or a high (H) level signal is displayed. Figs. 6 and 6B illustrate the signal detected by the sensor 230. Fig. 6A represents a signal at the time of regular operation. Fig. 6B represents a signal detected when no ink tank for color ink is installed. The normal operation of the carriage 211, the normal installation of the recording head, and the normal installation of each of the ink tanks are confirmed in the manner given below. As shown in Fig. 1 to Fig. 6, while monitoring signals from the sensor 230 immediately before a recording operation, the controller 234 controls the motor 235 for driving the carriage in order to allow the carriage 211 to scan at a speed slower than the traveling speed of the carriage in the usual recording operation. To slow down the scanning speed is to minimize any malfunction that may occur in detection. In synchronism with the traveling of the carriage 211, the signals from the sensor 230 are sensed. In a position where the end of the carriage 211 is supposed to be in a position immediately before the sensor 230, the S1 is sensed to examine whether or not the carriage 211 is in a normal operation. If no sense signal S1 is obtained at the juncture (that is, if it is an L level signal), the carriage operation is erroneous. Thus the controller 234 displays the carriage operation error on the indication panel 219. In the same way, the signal S2 from the sensor 230 in a position immediately before the ink tank 222 for color ink is sensed. If the signal is obtained, the operation is normal, but if no signal is obtained, it is determined that there is no installation of the ink tank 222 for color ink. Thus the controller 234 displays the color ink tank error on the indication panel 219. The same is applicable to the examination on the ink tank 221 for black ink. If an error indication is displayed, the recording operation is suspended. In the embodiment described in conjunction with Fig. 1 to Fig. 6B, an example is represented, in which both the recording head and the ink tanks are exchangeable. However, the above-mentioned is not limited to such an example. It is also applicable to a case where only the ink tanks are exchangeable or to a case where only the recording head is exchangeable. Also, in the above-mentioned embodiment, the description has been made of the case where the ink tanks are two. However, it is not limited to such a case only. The number of ink tanks may be only one for the use of black ink or three for the use of yellow, magenta, and cyan, respectively, or four for the use of yellow, magenta, cyan, and black, respectively. Further, an optical sensor is exemplified for use, but the sensor is not limited to the optical one. It may be possible to use a mechanical sensor, for example. Fig. 7A illustrates an example of a mechanical sensor. The carriage 211, each of the ink tanks 221 and 222, and the recording head 211 move correlatively to the main body of the recording apparatus in the direction indicated by an arrow C to abut on a mechanical switch 241. Then the mechanical switch 241 can obtain a signal shown in Fig. 7B. Fig. 7B illustrates the signal generated in a normal case. In this respect, it may also be possible to use a magnetic sensor for detection by forming an object to be sensed with a metal or a magnetic material. In addition to the above-mentioned embodiments, the ink remains for each color ink can be detected. Fig. 8 is a view showing a structure in which the detection of the ink remains is dually provided. This view represents the positional relationship between a recording head and a sensor, which are observed from behind. The photodetecting portion 232 of the sensor 230 is positioned in a location corresponding to the lower part of the ink tanks 221 and 222. In Fig. 8, the remains in the magenta ink tank (M) is small in the tank 222 for color ink. This results in an error for no magenta ink. The left end side of each of the ink tanks 221 and 222 is arranged to a reflective portion 237 which senses the presence or absence of the ink tank. The ink tank is made of a material having a good transparency of light so that the ink contained in it can be sensed directly. If the ink also has a good transparency of light, floats 236, 238, 239, and 240 are provided in each of the ink tanks 221 and 222. If the position of any one of the floats 236, 238, 239, and 240 is detected at a lower part in the ink tank, it is assumed that the ink remains in that particular tank are small or zero. Also, it is possible to detect the amount of ink in each of the ink tanks by arranging many numbers of photodetecting portions 232 of the sensor 230 over the depth direction of each ink tank. Now, in conjunction with Fig. 9, another embodiment will be described. Fig. 9 is a cross-sectional view showing an ink cartridge 320. The present embodiment shown in Fig. 9 does not need any float 236, and shows a different structure for detection. A detection sensor 321 for ink remains comprises a light emitting element 321a which emits infrared light 310 and a photodetecting element 321b capable of receiving light from the light emitting element 321a. An light reflection prism 321c is formed integrally with the ink cartridge 320 by polypropylene or some other almost transparent material. Thus, when there is no ink on the inclined surfaces of the head portion of the light reflection prism 321c, the beam from the light emitting element 321a is reflected and caused to arrive at the photodetecting element 321b. On the other hand, when the ink is filled around the inclined surfaces of the head of the light reflection prism 321c, the reflection of the beam from the light emitting element 321a is reduced. The luminous energy which can arrive at the photodetecting element 321b becomes small to make it possible to detect the presence or absence of ink. In this respect, a reference numeral 336 designates an ink supply outlet for supplying ink from the ink cartridge 320 to an ink jet recording head (not shown). Hereinafter, the principle of the detection will be described. The light reflection prism 321c has an angled part formed by inclined portions 341 and 342 almost at 90°. This angled part is arranged in the ink cartridge 320 in such a manner that the infrared light emitted from the light emitting element 321a is reflected by the inclined portion 341, and then, reflected again by the inclined portion 342 to return it to the photodetecting element 321b. Also, at least the part of the inclined portions 321 and 322 where the remains are detected (the position P in Fig. 9, for example) is formed by a material having a light transparency of the same refractive index as or an index extremely close to that of the liquid which is contained in the cartridge or either one side of the inclines portions 321 and 322 is treated by a mirror processing or the like so that the infrared light can be reflected. The specific principle of detection of the remains will be described as follows: The refractive index of the air is approximately 1.0; that of ink, approximately 1.4; and that of polypropylene, approximately 1.5. This is an exemplified material for the formation of the part of the inclined portion 341 or 342 of the light reflection prism 321c where the remains are detected. Here, (1) when ink is present in the ink cartridge 320, the reflective index of ink and that of the material of the part in the detecting position of the remains are extremely close to each other. Thus the infrared light 310 does not reflect on the inclined portion, and (2) if no ink is present in the ink cartridge 320, the reflective index of the air and that of the material of the part in the detecting position of remains are different. Thus the infrared light 310 reflects on the inclined portion. Then, the difference in the luminous energies arriving at the photodetecting element 321b at that time is transformed into electric signals by the known method of photoelectric transformation. In this way, it is possible to detect the presence or absence of ink in the ink cartridge 320. Here, as shown in Fig. 10, a plurality of ink cartridges are mounted on the carriage 351 movably together with the recording head 350. At the same time, each angled part formed by the inclined portions 321 and 322 is positioned upward in the ink cartridge, respectively. The inclined portions are formed by a material whose reflective index is extremely close to that of ink as described above. In this way, it is possible to detect the specific position of the liquid level of ink in each of the ink cartridges. Fig. 11 illustrates an example of electrical signal detected when the carriage on which a recording head and a plurality of ink cartridges are mounted together is moved against a detector 321. The carriage moves against the detector at a constant speed. When the tank Y for yellow ink passes, the detected signal Vout is at a low level 0v only for a time TV. Since this signal is detected in synchronism with the movement of the carriage, it is possible to recognize that it is a signal for the tank for yellow ink. Then, a TM is detected for the magenta tank M. Similarly, thereafter, a TC for the cyan, and a TBk for the black are detected. The low level time for the detected signal has a length which corresponds to the ink remains. In this way, not only the presence or absence of ink in each of the ink tanks can be detected, but also, the ink remains can even be detected. In this respect, the detection mechanism described in conjunction with Fig. 1 to Fig. 9 is capable of detecting the ink remains in the ink tank of such a structure where a recording head and an ink tank are formed together, in addition to being capable of detecting the ink remains in an ink cartridge. Further, it is possible for such a mechanism to detect the presence or absence of a recording head as well as a reading head arranged on a carriage. Also, there is no longer needed any flexible cable by providing the main body of a recording apparatus with a sensor which is capable of detecting at least one of the carriage and recording head. At the same time, the presence and absence of the recording head and the ink tank can be detected. As a result, a small motor can be employed for driving the carriage, thus making it possible to provide a small ink jet recording apparatus. Furthermore, it is possible to detect whether or not the carriage is in a normal operation at the same time. In this respect, the present invention produces an excellent effect on the recording head or the recording apparatus which is provided with means (such as electrothermal transducers, laser beam, or the like) for generating the thermal energy to be utilized as the energy, thereby the change of state of ink is created to discharge ink for recording, because with this method, it is possible to achieve a highly densified and precise recording. Regarding the typical structure and operational principle of such a method, it is preferable to adopt those which can be implemented using the fundamental principle disclosed in the specifications of U.S. Patent Nos. 4,723,129 and 4,740,796. This method is applicable to the so-called on-demand type recording system as well as to a continuous type recording system. Particularly, it is suitable for the on-demand type because the principle is such that at least one driving signal, which provides a rapid temperature rise beyond a departure from nucleation boiling point in response to recording information, is applied to an electrothermal transducer disposed on a liquid (ink) retaining sheet or liquid passage whereby to cause the electrothermal transducer to generate thermal energy to produce film boiling on the thermoactive portion of the recording head; thus effectively leading to the resultant one to one formation of a bubble in the recording liquid (ink) for each of the driving signals. By the development and contraction of the bubble, the liquid (ink) is discharged through a discharging port to produce at least one droplet. The driving signal is preferably in the form of pulses because the development and contraction of the bubbles can be effectuated instantaneously, thus discharging the liquid (ink) with particularly quick responses. The driving signal in the form of pulses is preferably such as disclosed in the specifications of U.S. Patent Nos. 4,463,359 and 4,345,262. In this respect, it is possible to execute an excellent recording in a better condition if the rate of the temperature increase of the heating surface is adopted as disclosed in the specification of U.S. Patent No. 4,313,124. The structure of the recording head may be as shown in each of the above-mentioned specifications wherein the structure is arranged to combine such discharge ports, liquid passages, and electrothermal transducers as disclosed in the specification (linear type liquid passage or right angle liquid passage). Here, there is also included in the present invention, a structure such as disclosed in the specifications of U.S. Patent Nos. 4,558,333 and 4,459,600 wherein the portions thermally activated are arranged in a curved area. In addition, the present invention is effectively applicable to the structure disclosed in Japanese Laid-Open Application No. 59-123670 wherein a common slit is used as the discharging ports for plural electrothermal transducers, and to the structure disclosed in Japanese Patent Laid-Open Application No. 59-138461 wherein an aperture for absorbing pressure wave of the thermal energy is formed corresponding to the discharging ports. In other words, according to the present invention, recording can be executed reliably and efficiently irrespective of the modes of the recording head. Moreover, as a recording head for which the present invention is effectively utilized, there is a full-line type recording head having a length corresponding to the maximum width of a medium which can be recorded by a recording apparatus. This full-line type head may be the one structured by combining a plurality of the recording heads disclosed in the above-mentioned specifications or a single full-line recording head which is integrally formed. In addition, the present invention is effectively applicable to a replaceable chip type recording head which is electrically connected with the main body of the apparatus, and to which the ink is supplied when it is mounted in the main assembly; or to a cartridge type recording head having an ink tank integrally provided for the head itself. Also, it is preferable to provide additionally means for recovering the recording head, and preliminarily auxiliary means as constituents of the recording apparatus according to the present invention because these additional means will contribute to making the effectiveness of the present invention more stabilized. To name them specifically, such constituents are capping means for the recording head, cleaning means, compression or suction means, preliminary heating means such as electrothermal transducers or heating elements other than such transducers or the combination of those types of elements, and the preliminary discharge mode which is adopted aside from the regular discharging for recording. Also, regarding the kinds or numbers of the installed recording heads, it may be possible to adopt a recording head having only one head for a single color besides those having a plurality of heads for plural kinds of ink having different colors and concentrations. In other words, as the recording mode of the apparatus, for example, the present invention is extremely effective in applying it not only to a recording mode in which only main color such as black or the like is used, but also to an apparatus having at least one of a multi-color mode with ink of different colors, or a full-color mode using the mixture of the colors, irrespective of whether the recording heads are integrally structured or it is structured by a combination of plural recording heads. Furthermore, in the embodiments according to the present invention set forth above, while the ink has been described as liquid, it may be an ink material which is solidified below the room temperature but liquefied at the room temperature. Since the ink is controlled within the temperature not lower than 30°C and not higher than 70°C in order to stabilize its viscosity for the provision of the stable discharge in general, the ink may be such that it can be liquefied when the applicable recording signals are given. In addition, while positively preventing the temperature rise due to the thermal energy by the use of such energy as an energy consumed for changing states of ink from solid to liquid, or using the ink which will be solidified when left intact for the purpose of preventing the ink from being evaporated, it may be possible to adopt for the present invention the use of an ink having a nature of being liquefied only by the application of thermal energy, such as an ink capable of being discharged as ink liquid by enabling itself to be liquefied anyway when the thermal energy is given in accordance with recording signals, and an ink which will have already begun solidifying itself by the time it reaches a recording medium. In such a case, it may be possible to retain the ink in the form of liquid or solid in the recesses or through holes of a porous sheet such as disclosed in Japanese Patent Laid-Open Application No. 54-56847 or 60-71260 in order to enable the ink to face the electrothermal transducers. For the present invention, the most effective method applicable to the various kinds of ink described above is the method in which the aforesaid film boiling can be implemented. Furthermore, as the mode of the recording apparatus according to the present invention, it may be possible to adopt a copying apparatus combined with a reader in addition to the image output terminal which is integrally or independently provided for a word processor, computer, or other information processing apparatus. Also, it may be possible to adopt among others a mode of a facsimile apparatus having transmission and reception functions.

Claims: An ink tank (320) for use in an ink jet recording apparatus, containing ink to be discharged from a recording head, comprising an ink supply section (336) for supplying ink to the outside of said ink tank, and parts (341, 342) provided on a portion of a predetermined wall of a plurality of walls constituting said ink tank, said parts (341, 342) are inclined with respect to each other, light (310) emitted from the outside of said ink tank (320) is reflected by one (341) of said inclined parts (341, 342) to another (342) of said inclined parts (341, 342) and said other part (342) reflects the light (310) outside of said ink tank (320), wherein an amount of light reflected by said inclined parts (341, 342) varies in accordance with the ink amount at at least one of said inclined parts in said ink tank. An ink tank according to claim 1, wherein one of said other parts reflects the light (310) in a direction substantially opposed to said incident direction of the light (310). An ink jet recording apparatus capable of mounting said ink tank according to claim 1 or 2, said apparatus comprising: a carriage (351) movable in a given direction with a recording head (350) which is detachably mounted thereon and which is provided with discharge ports for discharging ink, and said ink tank (320); and a sensor (321) for detecting the presence or absence of at least one of said carriage (351), said recording head (350) and said ink tank (320), said sensor (321) being provided on the main body of the recording apparatus and positioned within the movable range of said carriage (351), wherein said sensor (321) comprises a light emitting unit (321a) for emitting said light (310) from the outside of said ink tank and a photodetecting unit (321b) for receiving said reflected light (310). An ink jet recording apparatus according to claim 3, further comprising: a controller (234) for determining whether the movement of said carriage (351) is normal or abnormal, and whether at least either one of said recording head (350) and said ink tank (320) is installed by receiving from said sensor (321) the detected signal which is sensed in synchronism with the movement of said carriage (351). An ink jet recording apparatus according to claim 3 or 4, wherein said carriage (351) comprises a plural number of recording heads (350) and wherein one color of said ink is assigned to one of said recording heads (350), respectively. An ink jet recording apparatus according to one of claims 3-5, wherein said recording head (350) is provided with electrothermal transducers (204) for generating thermal energy for discharging ink. An ink jet recording apparatus according to one of claims 3-6, wherein said recording head (350) discharges ink from the discharge ports (207) by utilizing the film boiling to be generated in the ink by thermal energy which is applied by said electrothermal transducers (204). A method for determining an ink amount in an ink tank in an ink jet recording apparatus, said method comprising the steps of: emitting light (310) from the outside of said ink tank (320), reflecting said light (310) by one (341) of parts (341, 342) which are inclined with respect to each other, to another of said inclined parts, detecting the light reflected by said inclined parts; and determining the ink amount in said ink tank in accordance with an amount of the light detected at said detecting step, wherein an amount of light reflected by said inclined parts (341, 342) varies in accordance with the ink amount at at least one of said inclined parts in said ink tank.

Inventors: EBISAWA ISAO, HASHIMOTO KENICHIRO, INUI TOSHIHARU, MORIYAMA JIRO, SUGIYAMA HIROSHI, YAEGASHI HISAO, EBISAWA, ISAO, HASHIMOTO, KENICHIRO, INUI, TOSHIHARU, MORIYAMA, JIRO, SUGIYAMA, HIROSHI, YAEGASHI, HISAO, EBISAWA, ISAO, C/O CANON KABUSHIKI KAISHA, HASHIMOTO, KENICHIRO, C/O CANON KABUSHIKI KAISHA, INUI, TOSHIHARU, C/O CANON KABUSHIKI KAISHA, MORIYAMA, JIRO, C/O CANON KABUSHIKI KAISHA, SUGIYAMA, HIROSHI, C/O CANON KABUSHIKI KAISHA, YAEGASHI, HISAO, C/O CANON KABUSHIKI KAISHA
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1994
Main classification: B41J25
IPC codes: B41J29, B41J2, B41J25